Automatic soldering apparatus

ABSTRACT

A flux foaming unit, a preheating unit, a solder bath unit, and a cooling unit are arranged around an endless chain moving in a horizontal plane. By mounting a printed circuit board on a carrier attached to the endless chain, the board can be transported by means of the carrier and soldered automatically during its passage over each said unit.

United States Patent Kondo 1 1 Aug. 1, 1972 [54] AUTOMATIC SOLDERING2,770,875 11/1956 Zimmerman ..29/503 APPARATUS 2,776,640 l/1957Miklofsky et a1. ..118/74 3,163,146 12/1964 Hagner et a1. ..ll3/126 [72]fiz'g gf "i ii :il g i 'gg 3,482,755 12/1969 Raciti ..22s/34 g y a Y P3,574,934 4/1971 DeRose ..29/626 2 d: 2 l F116 June A970 FOREIGN PATENTSOR APPLICATIONS 1 APP! 8 628,778 10/1961 Canada ..228/37 [30] ForeignApplication Priority Data Primary Examiner-John F. Campbell AssistantExaminer-R. J. Craig June 28, 1969 Japan ..44/6069 9 Atmmey walterspruegel [52] U.S. Cl. ..228/37, 29/503, 29/626, 57 ABSTRACT 118/74,228/36 l 51 Int. 01. ..B23k 1/08 A fl foammg 3 a Pfeheatmg a Solder bath58 Field of Search .228/34, 35, 36, 37; 118/74; and P j arranged aroundan 29/503 626; 113/116 endless chain moving 1n a horizontal plane. Bymounting a printed circuit board on a carrier attached to the endlesschain, the board can be transported by means [56] References Cited ofthe carrier and soldered automatically during its UNITED STATES PATENTSPassage Over each said unit- 2,764,953 10/1956 Mullan ..1 13/59 3Claims, 14 Drawing Figures 6! 4! P; 7 8 I I v I I 7 r 9 G9 (O R Q m c: ll I I I l' TP'ATTENTEDAuc 1 I972 3.680.762

SHEET 1 0F 6 Prior Art INVENTOR PATENTEBAUB 1 I972 3.680.752

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INVENTOR Kama/71' A/0/7070 ATTORNEY PATENTEnAus 1 I972 3,680.762

sum 5 or 6 INVENTOR A ORNEY alssmsz PATENTEDMIB 1 m2 SHEET 6 OF 6 FEG.

IN VENTOR fins/71' ffozyao bath unit in a linear manner, pass a printedcircuit board over the units in succession by an endless carrying means,and automatically solder the board. According to this system, however,the total effective distance of carriage of the endless carrying meanscannot be fully utilized but only half of the entire length is used.

. Because of its linear arrangement the endless carrying means is muchelongated'in length, and this requires a larger space for installationrelative to the whole apparatus. Also, in the linear arrangement,'theprinted circuit board must be attached to the carrier when the carrierappears at one end of the endless carrying means (the return path of theendless carrying means normally runs underneath a table). It istroublesome for the operator to find the carrier when suddenly appearingfrom beneath the table and instantly attach the printed circuit board tothe carrier. Saidboard is auto matically disengaged from the carrier atthe other end of the endless carrying means and the carrier only returnsto said one end over the return path under the table. During the carrierreturn, the solder deposits and flux onthe carrier will drop andaccumulate on the bottom plate of the table support. The space betweenthis bottom plate and the carrier return path is usually relativelysmall so that the accumulated solder deposits will at times interferewith the endless carrying means.

A main object of the present invention is to overcome suchdisadvantages, utilize the entire length of the carrying meanseffectively for the operation, and thereby achieve economy and closerproximity to associated processes by smaller space for installation.

According to the invention, an automatic soldering apparatus comprisesendless carrying means revolving in a horizontal plane, a plurality ofcarriers each for supporting a plate member to be soldered, with thecarriers being removably attached to the endless carrying means andcirculating therewith in the horizontal plane, and arrangement of a fluxfoaming unit, a preheating unit, a solder bath unit, and a cooling unitdisposed in that order in a circle under a carrier track.

In this automatic soldering apparatus, a printed circuit board isautomatically soldered while it makes one round in a horizontal plane ona carrier driven by the endless carrying means. Thus, nearly the entirelength of the carrying means is effectively used for carrying out theprocess required for soldering. As each carrier can always be seen bythe operator, the loading of the carriers with boards is quite easy forhim, and as the carriers circulate in the horizontal plane the solderdeposits will not accumulate on the bottom plate of the table support asheretofore. The endless carrying means may preferably consist of anendless chain.

Another object of the invention is to provide a lead wire cutting unitfollowing the cooling unit. Thus, the soldering process and the cuttingof the lead wire of the soldered printed circuit board are carried outin a single operation for increased productivity.

Another object of the invention is to provide an automatic solderingapparatus which is provided with two series of the aforementioned unitsaround the endless carrying means, thus carrying out the solderingoperation in two steps. This system is specifically adapted for printedcircuit boards having relatively long lead wires.

Still another object of the invention is to improve the aforementionedunits.

The invention will be further explained, and other objects and featureswill become apparent, from the following description, with reference tothe accompanying drawings, in which:

FIG. 1 is a schematic diagram showing the construction of an automaticsoldering apparatus according to the invention;

FIG. 2 is a schematic diagram showing the construction of a knownautomatic soldering apparatus;

FIG. 3 is a plan view of a preferred embodiment of an automaticsoldering apparatus according to the invention;

FIG. 4 is a side elevation of the apparatus of FIG. 3;

FIG. 5 is a perspective view of a carrier adapted to be used in thesoldering apparatus; l

FIG. 6 is a sectional view taken along the line X-X ofFIG.5 v

FIG. 7 is a view showing a cross section of the construction of a fluxfoaming unit; v

FIG. 8 is a sectional view taken along the line Y-Y of FIG. 7;

FIG. 9 is a perspective view of a preheating unit;

FIG. 10 is a perspective view of a solder bath unit;

FIG. 1 1 is a perspective view of a solder pot;

FIG. 12 is a sectional view showing the construction of the jet bath;

' FIG. 13 is a perspective view, partly broken away, of the jet bath ofFIG. 12; and

FIG. 14 is a schematic diagram showing another embodiment of theinvention.

Referring now to FIG. 1, an endless chain 1 is provided at the center ofthe automatic soldering apparatus to revolve in a horizontal plane, towhich carriers 2 for printed circuit boards (not shown) are attached.Beneath the track on which the carriers 2 move there are disposed a fluxfoaming unit 3, a preheating unit 4, a solder bath unit 5, a coolingunit 6, and a lead wire cutting unit 7, in that order.

In the apparatus shown, each carrier 2 circulates along a rail (notshown) on the upper surface of the frame 9 of the apparatus, with thecarrier moving with the endless chain 1. Accordingly, each printedcircuit board to be soldered, when mounted on a carrier 2 andtransported thereby, is coated with foamed flux at the unit 3, preheatedat the unit 4, dipped in and soldered by the molten solder at the unit5, cooled at the unit 6, with the downwardly extending length of thelead wire cut off by the cutter 8 of the unit 7, thereby concluding asoldering process.

After being soldered, the printed circuit board is released from thecarrier 2 by a device not shown, with only the carrier being returned tothe initial position. In this position, another printed circuit board tobe soldered is placed on the carrier 2, thus repeating the cycle ofoperation.

FIG. 2 shows a known soldering apparatus in which identical parts aredenoted by identical numerals for each unit as in FIG. 1. In theapparatus shown, the units are provided in a linear arrangement asalready mentioned. Since the endless chain returns through a lowerpassage (not shown), the effective carrying length of the endless chainis merely one half of the entire length of the chain.

As may be apparent from comparison with the known apparatus of FIG. 2,the soldering apparatus according to the invention will effectivelyutilize the entire length of the chain, and the various units arearranged within a minimum space, whereby the whole apparatus will be ofsmall size. The apparatus of the invention incorporates a lead wirecutting unit, so that the lead wire can be out following the solderingprocess, thereby enhancing the efficiency of the production and adaptthe apparatus for mass production.

FIGS. 3 and 4 show a preferred embodiment of the invention. The endlesschain 1 is mounted on sprockets l and 1 l driven by a motor not shown. Asafety cover 12 is provided over the chain 1. The sprocket may be fixedon the frame 9 and the sprocket 11 can be adjusted at 13 for regulatingthe tension in the chain 1. The endless chain 1 is provided with anumber of carriers 2 for printed circuit boards at substantially equalintervals along its length. Underneath the track of the carriers arearranged, in that order, a flux foaming unit 3, a preheating unit 4, asolder bath unit 5, a cooling unit 6, and a lead wire cutting unit 7,with these units surrounding the endless chain 1. A control box of anelectrical system of the apparatus is designated at 14, includingdifferent pilot lamps at 15, switches at 16, a main power switch at 17,and inspection cover plates at 18 and 19.

Referring to FIGS. 5 and 6, each carrier 2 has a frame 20 ofsubstantially rectangular box-shape, the bottom surface of said framehaving a rectangular opening 21. At the fore and rear parts of thebottom surface of the carrier are formed elongated slots 22 and 22'respectively. Screw studs (not shown) at both ends of each of a pair ofmounting bars or angles 23 and 23' are inserted into said elongatedgrooves 22 and 22', with said screw studs threadedly receiving fasteners25 and 25' to rigidly secure the angles to the frame. The spacingbetween the angles 23 and 23 can be adjusted by loosening the fasteners25 and 25' to relatively move the angles. The angle 23 carries a supportmember or plate 27, and to the other angle 23' is hinged, at 26, asupport member or plate 27' with plate 27' is normally biased clockwiseby the spring 28 (FIG. 6). The lower ends of the support plates 27 and27 are provided with a longitudinally extending groove and projections,and the portions consisting of the grooves and the projections 29 and29' form gripping elements for the opposite edges of a printed circuitboard when the board is inserted between said portions against thebiasing force of the spring 28. The support plate 27' has an operatinghandle 24 secured thereto, with this handle passing through the opening21 and projecting upwardly in the frame 20. When a cam member (notshown) at a chosen location along the track of the carriers 2 contactsthe upper end of the operating rod 24, the support plate 27' is swungcounter-clockwise, resulting in release of a gripped circuit board andit will drop.

Fixed to one side of the frame 20 is a plate member 32 having two holes33 which receive two projecting link pins 34 provided on the endlesschain 1, whereby the carrier is removably attached to the endless chain.Also, a pair of rollers 30 on the same side of the frame 20 ride onguide rails 31 to prevent cocking of the carrier (FIG. 6). The carrier 2has on the other side a pair of wheels 34 rotatable on the rails 71 atthe upper surface of the frame 9.

There is removably mounted an auxiliary carrier 35 on the frame 20. Theauxiliary carrier 35 has a framelike fiat plate 36 with an opening inthe middle, a pair of guide rods 37 and 37' parallel to one pair ofopposite edges of said opening in, and spaced downwardly from, the plate36, with a large number of thin wires 38 being strung between said guiderods and parallel to each other. The flat plate 36 has on each of twoopposite sides two holes which receive studs 39 in the bottom of theframe 20 to locate the auxiliary carrier 35 on the frame 20. The thinwires 38 are at one end fixed to one side of the flat plate 36, and areat the other end secured to the other side of the flat plate 36 throughspring 38 which tension the wires. A printed circuit board can becarried by the auxiliary carrier 35 simply by placing the board on thewires 38.

Particulars of the flux foaming unit 3 of FIG. 3 are illustrated inFIGS. 7 and 8. The foaming unit has an outer vessel 40 and an innervessel 41, the latter vessel 41 providing a vessel proper 43 having anopening 42 communicating with the outer vessel, and a cap member 44fitted to the vessel proper 43 and having a rectangular nozzle 54 at thetop. Two opposite sides of the vessel proper 43 are provided with slots45 through which to insert from above two end caps of a foamer 46. Thefoamer 46 consists of a pair of end caps 47 and 47', a cylindricalfoaming tube 50 fitted between said end caps, and air ducts 48 and 49mounted within the foaming tube concentrically therewith. One end 49' ofthe air duct 49 is fixed in the central hole of the end cap 47', withthe other end thereof being threaded into the adjacent end of the airduct 48. The other end 48' of the air duct 48 is connected to the airpipe 51, and is closely fitted in the central hole of the end cap 47.The inner periphery of the end cap 47 has a sliding fit with the outerperiphery of the foaming tube 50, so that on rotating the air duct 48relative to the air duct 49 to thereby screw the latter into the former,the end cap 47 may be moved towards the end cap 47 Thus the foaming tube50 can be fitted between end caps and the length of the foamer 46 can beadjusted.

The foaming tube 50 consists of a sintered alloy, having greatmechanical strength and a great many fine pores. The air ducts 48 and 49have many openings 52 along their peripheries. The liquid flux isinjected into the vessel until it immerses at least the upper surface ofthe foaming tube 50. Accordingly, when compressed air passes from theair pipe 51 into the air ducts 48 and 49, it passes through the openings52 to the interior 53 of the foaming tube 50, thence passes through finepores in the wall of the foaming tube into the liquid flux to foam thesame. The foamed flux overflows at the nozzle 54 of the cap member 44and reaches, and is thus applied to, a passing printed circuit board. Alarge number of holes 52 in the air ducts serves to equalize the airpressure in the space 53 between the boaming tube 50 and the air ducts48 and 49 so that flux with small air bubbles will flow uniformly fromthe nozzle 54 throughout its length.

Details of the preheating unit 4 of FIG. 3 are shown in FIG. 9. The unit4 includes a casing 56 having a reflector plate 55 in the interiorthereof. A mounting bar 58 to which a sheathed heater 57 is attached issecured to one side of the casing 56 by means of a plurality of hinges59. Therefore, the heater 57 and the mounting bar 58 can be turned inthe direction of the arrow F, and thus the heater 57 can be retractedfrom the shown operative position in the casing 56 for the purpose ofaccumulated flux which drops into the casing 56. The casing hasprojecting mounting lugs 60. The heater 57 serves for preheating thecircuit boards, resulting in reduction of heat sinking on parts of theprinted circuit boards or on the surfaces of the boards and inactivating the flux.

Particulars of the solder bath unit 5 of FIG. 3 are illustrated in FIGS.to 12. Referring to FIG. 10, the unit 5 includes an outer casing 65, asolder pot 66 inserted in the casing, and a jet bath 67 inserted in saidsolder pot. As best shown in FIG. 11, there are arranged on the sidewalls of the solder pot a sheathed heater 68 for solder melting and asheathed heater 69 for controlling the temperature of the molten solder,with each of these heaters consisting of three heater elements connectedin delta. At the bottom of the solder pot 66 is provided anothersheathed heater 70 (not shown) for use if needed. Each heater 68 to 70has terminals 68' to 70', respectively. Connected in series with theheater 68 is a thermostat (not shown). When the solder in the pot isheated to a temperature at which it melts, the thermostat will stop theflow of current through the heater 68. The temperature of the moltensolder is maintained constant by a temperature control means having aplatinum resistor (not shown) and onoff control for current flow throughthe heater 69.

The jet bath 67 comprises, as seen in FIGS. 12 and 13, a solder suctionportion 74, a nozzle portion 75, and a conduit portion 76 connectingboth portions. The suction portion 74 has side walls provided with asolder discharge opening 79, a bottom plate 80 with a solder suctionopening 78, and a cover plate 81. In the space 82 within by members 77,80, and 81 is arranged a pump wheel 83. The shaft 84 of the pump wheel83 extends upwardly through an opening in the cover plate 81 and is heldin a bearing 89 on a bridging plate 85 (FIG. 10), and this shaft isdriven by a motor 86 on the casing 65 through speed changing means 87and a belt drive 88.

The nozzle portion 75 has a lower part 90 flaring funnel-like upwardlyfrom the solder inlet 94 at the bottom, an upper part 91 mounted on saidlower part and flaring upwardly in inverted-funnel fashion (FIG. 13) aturbulence flow control plate 92 mounted in the vicinity of the junctionof the upper and the lower parts and having a number of holes 92', and arectification plate 93 vertically extending in the middle of the upperpart. The solder inlet 94 communicates with the suction portion 74through the inclined conduit portion 76.

As the pump wheel 83 is driven by the motor 86, the molten solder flowsfrom the pot 66 into the space 82 through the suction opening 78 and ispassed to the conduit portion 76 by a flow control plate 95. The moltensolder then flows downwardly in the conduit 76 to the solder inlet 94and then rises in the funnel-shaped lower port. The molten solder, whichis powerfully stirred by the pump wheel 83 and hence is in violentturbulence, becomes increasingly less turbulent on its flow through thedownwardly inclined conduit portion 76 and the lower part of expandingfunnel shape. The solder flow is further moderated by turbulence flowcontrol plate 92 and'flow direction control plate 93. Thus, the solderflow subsides to a mild solder flow wave of remarkably uniform heightover the length of the nozzle 96, and spurts from the nozzle 96. When aprinted circuit board passes the solder flow wave, the latter contactsthe lower surface of the board which thus becomes soldered. The leadwires project downwardly from the lower surface of the board, so thatthe level of the solder wave must be higher than the length of theprojecting lead wires in order to reach the board. The height of thewave can readily be adjusted by the speed changer 87.

While soldering of printed circuit boards is carried out, it sometimesoccurs that solder icicles or bridges form on the soldered surface of aboard. These solder icicles or bridges can be removed by a solderconducting plate 97. This plate 97 consists of a single board memberwhich with its bent edge is secured to the nozzle 96, and is inclineddownwardly away therefrom. The conducting plate is at its opposite edgeformed as an upwardly curved lip portion 98. The molten solder spurtsfrom the nozzle 96 and is then divided to left and right, with themolten solder flowing over the conducting plate 97 being raised again bythe raised lip portion 98, resulting in a small wave of molten solderthereat. Since-the conducting plate extends from the side of the nozzle96 leading in the travel direction of the printed circuit boards, thesolder icicles or bridges can be completely removed by this secondsolder wave.

Reverting now to FIG. 1, the cooling unit 6 consists of a known airblower having a motor and a fan, with the front of the blower beingprovided with a protection screen 6' (FIG. 3). A printed circuit boardsoldered in the manner described hereinbefore is rapidly cooled onpassing the cooling unit 6. By such cooling, the mechanical strength ofthe adhered solder can be ensured, as well as surface brightnessimproved. Furthermore, a printed circuit board deformed in being heatedin the soldering procedure, can be reformed by the cooling.

In case the lead wires projecting from printed circuit boards arerelatively long, the molten solder wave spurting from the nozzle 96 mustbe at a correspondingly high level to reach the boards. As the level ofthe solder wave increases, however, it becomes difficult to keep thewave level uniform over the length of the nozzle 96. In that case, it ispreferred to perform the soldering operation in two steps. FIG. 14 showsan apparatus for performing the soldering in such two steps, in whichadditional units 3' to 6, which are identical with units 3 to 6 in FIG.1, are arranged, in that order, following the unit 7 (FIG. 14). Inoperation, the wave of the molten solder at the solder bath unit 5 isset to a high level in accord with the length of the projecting leadwires, whereas the wave of molten solder at the solder bath unit 5' isset to a relatively low level. The initial soldering can be carried outin the above described manner by the units 3 to 6. In the unit 7, theelongated projecting lead wires are cut off. In this initial solderingprocedure the solder wave will be set for such a high level thataccurate soldering of the details of a printed circuit will not beachieved, for there often remain unsoldered portions. Therefore, thesecond soldering procedure is preferably carried out by the units 3' to6. Since the projecting lead wires have been cut off already by the unit7, the level of the molten solder wave in the unit can be set lower,whereby a solder wave at a uniform level throughout can be obtained.Thus, accurate soldering can be effected, and solder bridges and otherfailures produced in the initial soldering can also be fully removed.

What is claimed is:

1. Automatic soldering apparatus, comprising endless carrying meansmoving in a given direction in a circuitous path in a horizontal plane;a plurality of carriers for removably carrying printed circuit boardswith lead wires depending from one face, with said carriers beingconnected with said endless carrying means for movement therewith; trackmeans supporting said carriers for movement in said horizontal plane andwith said one face of circuit boards carried thereby being horizontallydisposed and facing downwardly; a first series of successiveflux-foaming, preheating, and solder bath units beneath said carriers,and being in flux-applying, preheating, and solder-applying relation,respectively, with said one face of circuit boards on passing carriers,of which said solder bath and fluxfoaming units are leading andtrailing, respectively, in said given direction, and said solder. bathunit having a nozzle and a continuous solder wave issuing therefrom andoverflowing thereat, with said nozzle being spaced from said one face ofcircuit boards on passing carriers to clear depending lead wiresthereon, and said overflowing solder wave having a sufficiently highcrest to contact said one face of circuit boards on passing carriers; alead wire cutting unit beneath said carriers and spaced from said solderbath unit in said given direction, and being in lead-cutting relationwith circuit boards on passing carriers; another series of secondsuccessive flux-foaming, preheating and solder bath units beneath saidcarriers, and being in flux-applying, preheating and solder-applyingrelation, respectively with said one face of circuit boards on passingcarriers, with said other series of units being spaced from said leadwire cutting unit, and said second solder bath and flux-foaming unitsbeing leading and trailing in said given direction, and said secondsolder bath unit being identical with that of said first series, exceptthat said nozzle of said second solder bath is closer to said one faceof circuit boards on passing carriers.

2. Automatic soldering apparatus as in claim 1, wherein each of saidflux-foaming units provides an outer vessel, an inner vessel incommunication with said outer vessel and having a top nozzle below saidone face of circuit boards on passing carriers, with said vesselsholding a supply of flux liquid, a foamer immersed in flux liquid insaid inner vessel, said foamer having a porous foaming tube, a pair ofend caps supporting said foaming tube in said inner vessel, two airducts extending in said foaming tube, the outer ends of said air ductsbeing closely fitted into said end caps, respectively, and

the th r ends thereof bein th ea d connect d, a d an air p ipe connectedto on e of sa ai ducts, with said air ducts having a large number ofholes throughout their peripheries to equalize the air pressure in thespace between the foaming tube and the air ducts therein and therebybring about uniform flux foaming from the whole outer periphery of thefoaming tube.

3. Automatic soldering apparatus as in claim 1, wherein each of saidpreheating units provides a casing, a sheathed heater, and a mountingbar carrying said heater, with said bar being hinged to said casing,whereby said heater is turnable from its operative position in saidcasing to the out-side of the casing.

1. Automatic soldering apparatus, comprising endless carrying meansmoving in a given direction in a circuitous path in a horizontal plane;a plurality of carriers for removably carrying printed circuit boardswith lead wires depending from one face, with said carriers beingconnected with said endless carrying means for movement therewith; trackmeans supporting said carriers for movement in said horizontal plane andwith said one face of circuit boards carried thereby being horizontallydisposed and facing downwardly; a first series of successiveflux-foaming, preheating, and solder bath units beneath said carriers,and being in flux-applying, preheating, and solderapplying relation,respectively, with said one face of circuit boards on passing carriers,of which said solder bath and fluxfoaming units are leading andtrailing, respectively, in said given direction, and said solder bathunit having a nozzle and a continuous solder wave issuing therefrom andoverflowing thereat, with said nozzle being spaced from said one face ofcircuit boards on passing carriers to clear depending lead wiresthereon, and said overflowing solder wave having a sufficiently highcrest to contact said one face of circuit boards on passing carriers; alead wire cutting unit beneath said carriers and spaced from said solderbath unit in said given direction, and being in leadcutting relationwith circuit boards on passing carriers; another series of secondsuccessive flux-foaming, preheating and solder bath units beneath saidcarriers, and being in flux-applying, preheating and solder-applyingrelation, respectively with said one face of circuit boards on passingcarriers, with said other series of units being spaced from said leadwire cutting unit, and said second solder bath and flux-foaming Unitsbeing leading and trailing in said given direction, and said secondsolder bath unit being identical with that of said first series, exceptthat said nozzle of said second solder bath is closer to said one faceof circuit boards on passing carriers.
 2. Automatic soldering apparatusas in claim 1, wherein each of said flux-foaming units provides an outervessel, an inner vessel in communication with said outer vessel andhaving a top nozzle below said one face of circuit boards on passingcarriers, with said vessels holding a supply of flux liquid, a foamerimmersed in flux liquid in said inner vessel, said foamer having aporous foaming tube, a pair of end caps supporting said foaming tube insaid inner vessel, two air ducts extending in said foaming tube, theouter ends of said air ducts being closely fitted into said end caps,respectively, and the other ends thereof being threadedly connected, andan air pipe connected to one of said air ducts, with said air ductshaving a large number of holes throughout their peripheries to equalizethe air pressure in the space between the foaming tube and the air ductstherein and thereby bring about uniform flux foaming from the wholeouter periphery of the foaming tube.
 3. Automatic soldering apparatus asin claim 1, wherein each of said preheating units provides a casing, asheathed heater, and a mounting bar carrying said heater, with said barbeing hinged to said casing, whereby said heater is turnable from itsoperative position in said casing to the out-side of the casing.